Selected property of Choice within Taxonomy does not work

[DanieliusV]

Hello! I believe there is a bug with selected property of Choice tag when used within Taxonomy. It can be reproduced in the playground and occurs in multiple different versions.

Bug description
When Choice is provided with selected="true" property it works with no problems within Choices, but not within Taxonomy.

Bug cause
After briefly looking through the code, it seems that this property is not supported at all within Taxonomy. It does not add pre-selections on lines 570-572 in AnnotationStore (which seems to be easily solvable by making it support both choices and taxonomy). In order to do that, it needs to know node.preselectedValues, which even after importing SelectedModelMixin I could not get working, as it fails to get an array containing the full path - and gets only the last choice instead.

[makseq]

@DanieliusV Hello! It's a very cool idea! Could you become a contributor and send us your valuable PR?